05 October 2015

The question of how "traditional conference publication" should react to arxiv prepublications is raised quite frequently. I'm not particularly shy about the fact that I'm not a fan, but that's not what this post is about. This post is about data.

In any discussion about the "arxiv question," proponents of the idea typically cite the idea that by posting papers early on arxiv, they are able to get feedback from the community about their work. (See for example here, which at least tries to be balanced even if the phrasing is totally biased, for instance in the poll at the end :P.)

At any rate, the question I was curious about is: is this actually borne out in practice?

I did the following experiment. Arxiv nicely lets us see revision histories. So we can see, for instance, whether a paper that was placed on arxiv before notifications for the corresponding conference have gone out, is updated more than a paper that was placed on arxiv after notifications.

For NIPS papers that were first posted to arxiv after camera ready, 75% were never updated and 19% were updated once (on average, they were updated 0.36 times +- 0.713 std).

For papers that were first posted to arxiv before notification, all were updated at least once. The real question is: how many times were they updated between posting to arxiv and acceptance to the conference. The answer is that 82% were never updated during that period. Of course, all were updated at some point later (after the camera ready deadline), and 55% were updated only once, and another 18% were updated twice.

[Note: I only count updated that come at least two week after the first posting to arxiv because before is more likely to be typo fixing, rather than real feedback from the community.]

The sample size is small enough that I can actually look at all of the ones that were updated between posting to arxiv and notification. One of these seems was first posted in mid-Feb, updated twice is late March, and then again in Nov (acceptance) and Dec (camera ready). Another is very similar. Two were most likely posted the previous year when it was submitted to AIStats (the dates match up) and then updated when submitted to NIPS. Those were the only four, and two of them seem like a legit possible case of update due to community feedback.

As far as the question of "rapid impact on the field" this is harder to answer. I took a random sample of ten papers from each of the groups (prepub versus non-prepub) and got citation counts from google scholar. The median citation count was 10 for both sets. The average was slightly higher for the prepub set (15 versus 11, but with giant standard deviations of 12 and 16). Considering the prepub set has been out at least 6 months longer (this is NIPS 2013 and 2014 so this is a sizeable percentage), this is a pretty small difference. And it's a difference that might be attributable to other factors like "famous people are perhaps more likely to prepub" [actually it's not clear the data play this out; in a totally unscientific study of "does Hal think this person is famous" and a sample of 20 for each, it's even split 10/10 in both sets].

Anyway, I'm posting this because I've heard this argument many times and I've always felt it's a bit dubious. I've never seen data to back it up. This data suggests it's not true. If someone really believes this argument, it would be nice to see it backed up with data!

[Notes: I took only papers that were marked on arxiv as having appeared in NIPS, and which were first posted to arxiv in 2013 or 2014; this is 175 papers. I then hand-checked them all to exclude things like workshops or just submissions, and labeled them as to whether they appeared in 2013 or 2014. That left a sample of papers. The rest of the data was extracted automatically from the arxiv abstract. The total number that was posted before notification (the prepub cases) is 22 (or 27%) and the total number that were posted after notification is 59 (or 73%). So the sample is indeed small. Not much I can do about that.]